scholarly journals Enhanced Luminescence of Silver Nano-particles Doped Na2O-BaO-Borate Glasses

2020 ◽  
Vol 9 (2) ◽  
pp. 107-119
Author(s):  
Rajeshree Patwari D ◽  
B Eraiah
Keyword(s):  
Band Gap ◽  
Visible Region ◽  
Rare Earth Ions ◽  
Lanthanide Ions ◽  
Nano Particles ◽  
Electromagnetic Spectrum ◽  
Borate Glasses ◽  
Nonlinear Behaviour ◽  
Plasmon Band ◽  
Opposite Manner

 Na2O-BaO-Borate glasses were synthesized with silver nano-particles of varying silver concentrations by the method of melt-quenching. Their densities of the glasses and hence molar volumes were computed. The existence of the silver nano-particles was depicted by characteristic band in the absorption spectra of UV- Visible studies known as plasmon band. Further the matrix also showed a small amount of nanostructures of the host which imparts the nonlinear behaviour. They were further visualized by the Scanning and Transmission electron microscopy. Optical band gap and Urbach energies were found. The band gap values change exactly in the opposite manner of density with silver doping. The wide luminescence band in the visible region formed for the excitation of plasmon band may be utilized for the luminescence enhancement of luminescent material like rare earth ions. The very significant result perceived from this is that the glass as such with silver nano-particles showed broad emission in the, green & blue portions of electromagnetic spectrum in the close vicinity of white light with the variation of silver content which can be utilized for the enrichment of the emission of lanthanide ions in the visible section of electro-magnetic spectrum.

scholarly journals Electronic, Structural, and Optical Structure of Mono-Doped and Co-Doped (210) TiO2 Brookite Surfaces for Application in Dye-Sensitized Solar Cells—A First Principles Study

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3918
Author(s):  
Ratshilumela S. Dima ◽  
Lutendo Phuthu ◽  
Nnditshedzeni E. Maluta ◽  
Joseph K. Kirui ◽  
Rapela R. Maphanga
Keyword(s):  
Solar Cells ◽  
Band Gap ◽  
Dye Sensitized Solar Cells ◽  
Visible Region ◽  
Electromagnetic Spectrum ◽  
Doped Tio2 ◽  
Dye Sensitized ◽  
Sensitized Solar Cells ◽  
Co Doped ◽  
Optical Structure

Titanium dioxide (TiO2) polymorphs have recently gained a lot of attention in dye-sensitized solar cells (DSSCs). The brookite polymorph, among other TiO2 polymorphs, is now becoming the focus of research in DSSC applications, despite the difficulties in obtaining it as a pure phase experimentally. The current theoretical study used different nonmetals (C, S and N) and (C-S, C-N and S-N) as dopants and co-dopants, respectively, to investigate the effects of mono-doping and co-doping on the electronic, structural, and optical structure properties of (210) TiO2 brookite surfaces, which is the most exposed surface of brookite. The results show that due to the narrowing of the band gap and the presence of impurity levels in the band gap, all mono-doped and co-doped TiO2 brookite (210) surfaces exhibit some redshift. In particular, the C-doped, and C-N co-doped TiO2 brookite (210) surfaces exhibit better absorption in the visible region of the electromagnetic spectrum in comparison to the pure, S-doped, N-doped, C-S co-doped and N-S co-doped TiO2 brookite (210) surfaces.

scholarly journals Upconversion and Spectroscopic Properties of Rare Earth Codoped Lead Borate Glass Matrix

2017 ◽  
Vol 14 (2) ◽  
pp. 140-145 ◽  
Author(s):  
K. Goud ◽  
Ch. Ramesh ◽  
B. Appa Rao
Keyword(s):  
Rare Earth ◽  
Visible Region ◽  
Branching Ratio ◽  
Life Time ◽  
Rare Earth Ions ◽  
Borate Glasses ◽  
Energy Transfer Mechanism ◽  
Lead Borate ◽  
Ofelt Theory ◽  
Laser Materials

To develop efficient upconversion laser materials in the visible region an active lead borate glasses doped with Er3+/Yb3+ rare earth ions (GEY) has been studied extensively. In this investigation characterization techniques like Optical absorption, FTIR and photoluminescence were recorded and the data was analyzed. To evaluate the values of Ω2, Ω4 and Ω6 Judd-Ofelt theory has been applied to the f ↔ f transitions. Based on Judd–Ofelt theory branching ratio (βr) oscillator strength and the radiative life time (τR) values were determined. The upconversion spectra exhibited three emission bands at around 525 nm (2H11/2 ® 4I15/2), 545 nm (4S3/2 ® 4I15/2) and 660 nm (4F9/2 ® 4I15/2). The energy transfer mechanism between Yb3+ and Er3+ was discussed very clearly. Comparing the data obtained in other Er3+/Yb3+ doped materials, the lead bismuth gallium borate glasses doped with 0.6 mol% of Er2O3­/0.2 mol% of Yb2O3 ions are suitable materials for developing red upconversion lasers in the visible region.

scholarly journals Spray Pyrolysed Nanostructured Gold-Doped Tin Oxide (Auto) Thin Films

2021 ◽  
Vol 25 (4) ◽  
pp. 567-572
Author(s):  
S.I. Akinsola ◽  
K.S. Adedayo ◽  
A.B. Alabi ◽  
D.B. Olanrewaju ◽  
A.A. Ajayi ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Band Gap ◽  
Spray Pyrolysis ◽  
Tin Oxide ◽  
Visible Region ◽  
Oxide Thin Film ◽  
Sno2 Thin Film ◽  
Chemical Spray Pyrolysis ◽  
Electromagnetic Spectrum

Nanostructured SnO2 thin films were grown by the chemical spray pyrolysis (CSP) method. Homemade spray pyrolysis technique is employed to prepare thin films. SnO2 is wide band gap semiconductor material whose film is deposited on glass substrate. A gold nanoparticle-doped tin oxide thin film (AuTO) was also prepared. UV-VIS (ultraviolet visible) spectroscopy and four-point probe analysis are done for optical and electrical analysis. UV-Visible absorption spectra show that the band gap of SnO2 thin film is 3.78 eV and 3.82 eV for AuTO. Band gap of SnO2 thin film can be tuned that it can be used in optical devices. The films have transmittance increases (to about 60%) and the absorbance decreases in the visible region of the electromagnetic spectrum. The electrical conductivity of the Tin Oxide is enhanced by functionalizing with the Gold nanoparticles. It is higher than that of the Tin oxide only; 0.77 x 10-2 (Ohm cm)-1 and 3.55 x 10-2 (Ohm cm)-1 for SnO2 and AuTO respectively. These properties reveal that Tin Oxide doped with gold can actually be a good material for a transparent conducting oxide to be used in photovoltaic fabrication and in electronics.

scholarly journals Synthesis, spectroscopic, electrochemical and photophysical properties of high band gap polymers for potential applications in semi-transparent solar cells

BMC Chemistry ◽  
2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Peshawa O. Amin ◽  
Kamal Aziz Ketuly ◽  
Salah Raza Saeed ◽  
Fahmi F. Muhammadsharif ◽  
Mark D. Symes ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Refractive Index ◽  
Solar Cells ◽  
Band Gap ◽  
Optical Conductivity ◽  
Visible Region ◽  
High Energy ◽  
Electromagnetic Spectrum ◽  
High Energy Part ◽  
Energy Part

Abstract Background The design of new polymers able to filter the electromagnetic spectrum and absorb distinctly in the UV and high-energy part of visible spectrum is crucial for the development of semi-transparent solar cells. Herein, we report on the synthesis and spectroscopic, electrochemical, and photophysical characteristics of three new polymers, namely (i) Poly(triamterene-co-terephthalate), (ii) Poly[triamterene-co- 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine-p,p′-disulfonamide], and (iii) Poly(5-hydroxyindole-2-carboxylate) that might show promise as materials for semi-transparent solar cells. Results The energy band gap, refractive index, dielectric constant, and optical conductivity of the electron donor polymer, poly(triamterene-co-terephthalate), were determined to be 2.92 eV, 1.56, 2.44 and 2.43 × 104 S cm−1, respectively. The synthesized electron acceptor polymers showed a relatively high refractive index, dielectric constant, and optical conductivity. The presence of a direct allowed transition was confirmed between intermolecular energy bands of the polymers. Conclusions The polymers showed relatively high energy gap and deep HOMO levels, making them strong absorbers of photons in the UV region and high energy part of the visible region. The synthesized donor and acceptors performed well relative to P3HT and fullerenes due to the close match of the HOMO and LUMO levels. With further development, the polymers could be viable for use as the active layers of semi-transparent solar cells.

Luminescence and Time-Resolved Emission Spectra of Nd3+and Er3+: Silver Zinc Borate Glasses

2013 ◽  
Vol 207 ◽  
pp. 37-53
Author(s):  
João Coelho ◽  
Graham Hungerford ◽  
Sooraj Hussain Nandyala
Keyword(s):  
Steady State ◽  
Visible Region ◽  
Glass Network ◽  
Emission Spectra ◽  
Rare Earth Ions ◽  
Zinc Borate ◽  
Luminescence Spectra ◽  
Borate Glasses ◽  
Time Resolved ◽  
Spectral Profiles

The paper reports the visible-NIR luminescence and time-resolved emission spectral profiles of Nd3+, and Er3+ doped silver zinc borate glasses. Steady state luminescence (SSL) and time-resolved emission spectroscopy (TRES) were used to evaluate how the randomness of the network can influence the emission from rare earth ions in the visible region. As expected the composition of the glasses strongly influences the emission bands of the dopant ions. The lack of homogeneity in the glass network results in distorted and broad luminescence spectra. Moreover, time-resolved techniques allowed the visualization of the time dependence of the spectra. The luminescence was also characterized using steady state techniques and the strongest NIR emission peaks were 4F3/2 à 4Il1/2 for Nd 3+ and 4I13/2 à 4Il5/2 for Er 3+ ions respectively.Key words: Time-resolved emission spectra; decay associated spectra; Nd3+ and Er3+; Silver zinc borate glasses

Kathodo- und Photolumineszenz der Seltenerd-aktivierten Wirtsgitter Ba2La2B2+Te2O12 (B = Zn, Mg)

1986 ◽  
Vol 41 (6) ◽  
pp. 866-870 ◽  
Author(s):  
H.-D. Autenrieth ◽  
S. Kemmler-Sack
Keyword(s):  
Electronic Structure ◽  
Rare Earth ◽  
Visible Region ◽  
Host Lattice ◽  
Rare Earth Ions ◽  
New Host ◽  
Emission Efficiency ◽  
Transfer Processes ◽  
Trivalent Rare Earth ◽  
Host Lattices

By activation of the new host lattices Ba2La2B2+Te2O12 (B = Zn, Mg) with trivalent rare earth ions Ln3+ = Pr. Sm, Eu, Tb, Dy, Ho, Tm an emission in the visible region is observed. The influence of the electronic structure and concentration on the relative emission efficiency as well as the host lattice participation in the energy transfer processes are discussed.

Hydrothermal Synthesis of Nanosized Titania Photocatalysts Using Novel Water-Soluble Titanium Complexes

2007 ◽  
Vol 124-126 ◽  
pp. 723-726 ◽  
Author(s):  
Makoto Kobayashi ◽  
Koji Tomita ◽  
Valery Petrykin ◽  
Shu Yin ◽  
Tsugio Sato ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Specific Surface ◽  
Single Phase ◽  
Visible Region ◽  
Water Soluble ◽  
No Oxidation ◽  
Nano Particles ◽  
Titanium Complexes ◽  
Uv Visible

Highly crystalline titania nano-particles were synthesized by hydrothermal method using novel stable water-soluble titanium complexes. It was confirmed that single phase anatase, rutile and brookite, which can be rarely synthesized as a single phase, can be obtained by varying the ligand in the complex and pH of the aqueous solution. TEM observations and BET specific surface area measurements had shown that these samples consisted of nanosized particles of 5~200 nm and had high specific surface areas of 25~150 m2/g. According to UV-visible diffuse reflectance spectra, these titania samples absorbed light in the visible region (λ > 400 nm). Photocatalytic activities in NO oxidation reaction exhibited by synthesized titania powders under the irradiation by UV- visible light were higher than the activity of the commercial TiO2 photocatalyst P25 (Degussa). Especially, under illumination by only visible light of above 510 nm wavelength, photocatalytic activity of the obtained specimens exceeded that of P25 more than four times. We also clearly demonstrated that single phase brookite had high photocatalytic activity for NO oxidation.

Emergent chiroptical properties in supramolecular and plasmonic assemblies

2021 ◽  
Author(s):  
N. S. Shahana Nizar ◽  
Meleppatt Sujith ◽  
K. Swathi ◽  
Cristina Sissa ◽  
Anna Painelli ◽  
...  
Keyword(s):  
Visible Region ◽  
Electromagnetic Spectrum ◽  
Comprehensive Description ◽  
Chiroptical Properties ◽  
Uv Visible

This tutorial provides a comprehensive description of the origin of chiroptical properties of supramolecular and plasmonic assemblies in the UV–visible region of the electromagnetic spectrum.

scholarly journals Properties of Novel Non-Silicon Materials for Photovoltaic Applications: A First-Principle Insight

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2006 ◽  
Author(s):  
Murugesan Rasukkannu ◽  
Dhayalan Velauthapillai ◽  
Federico Bianchini ◽  
Ponniah Vajeeston
Keyword(s):  
Band Gap ◽  
Density Functional ◽  
Crystalline Silicon ◽  
Visible Region ◽  
Initial Population ◽  
First Principle ◽  
Direct Band Gap ◽  
Depth Analysis ◽  
Photovoltaic Applications ◽  
Direct Band

Due to the low absorption coefficients of crystalline silicon-based solar cells, researchers have focused on non-silicon semiconductors with direct band gaps for the development of novel photovoltaic devices. In this study, we use density functional theory to model the electronic structure of a large database of candidates to identify materials with ideal properties for photovoltaic applications. The first screening is operated at the GGA level to select only materials with a sufficiently small direct band gap. We extracted twenty-seven candidates from an initial population of thousands, exhibiting GGA band gap in the range 0.5–1 eV. More accurate calculations using a hybrid functional were performed on this subset. Based on this, we present a detailed first-principle investigation of the four optimal compounds, namely, TlBiS2, Ba3BiN, Ag2BaS2, and ZrSO. The direct band gap of these materials is between 1.1 and 2.26 eV. In the visible region, the absorption peaks that appear in the optical spectra for these compounds indicate high absorption intensity. Furthermore, we have investigated the structural and mechanical stability of these compounds and calculated electron effective masses. Based on in-depth analysis, we have identified TlBiS2, Ba3BiN, Ag2BaS2, and ZrSO as very promising candidates for photovoltaic applications.

scholarly journals Effect of thickness on the optical properties of Gaas thin films

2013 ◽  
Vol 37 (1) ◽  
pp. 83-91 ◽  
Author(s):  
Chitra Das ◽  
Jahanara Begum ◽  
Tahmina Begum ◽  
Shamima Choudhury
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Refractive Index ◽  
Band Gap ◽  
Optical Band Gap ◽  
Visible Region ◽  
Solar Spectrum ◽  
Band Gap Energy ◽  
Optical Parameters ◽  
Gap Energy

Effect of thickness on the optical and electrical properties of gallium arsenide (GaAs) thin films were studied. The films of different thicknesses were prepared by vacuum evaporation method (~10-4 Pa) on glass substrates at a substrate temperature of 323 K. The film thickness was measured in situ by a frequency shift of quartz crystal. The thicknesses were 250, 300 and 500 nm. Absorption spectrum of this thin film had been recorded using UV-VIS-NIR spectrophotometer in the photon wavelength range of 300 - 2500 nm. The values of some important optical parameters of the studied films (absorption coefficient, optical band gap energy and refractive index; extinction co-efficient and real and imaginary parts of dielectric constant) were determined using these spectra. Transmittance peak was observed in the visible region of the solar spectrum. Here transmittance showed better result when thicknesses were being increased. The optical band gap energy was decreased by the increase of thickness. The refractive index increased by increasing thickness while extinction co-efficient and real and imaginary part of dielectric constant decreased. DOI: http://dx.doi.org/10.3329/jbas.v37i1.15684 Journal of Bangladesh Academy of Sciences, Vol. 37, No. 1, 83-91, 2013

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